Many companies and other organizations operate computer networks that interconnect numerous computing systems to support their operations, such as with the computing systems being co-located (e.g., as part of a local network) or instead located in multiple distinct geographical locations (e.g., connected via one or more private or public intermediate networks). For example, data centers housing significant numbers of interconnected computing systems have become commonplace, such as private data centers that are operated by and on behalf of a single organization and public data centers that are operated by entities as businesses to provide computing resources to customers. Some public data center operators provide network access, power, and secure installation facilities for hardware owned by various customers, while other public data center operators provide “full service” facilities that also include hardware resources made available for use by their customers. As the scale and scope of typical data centers has increased, the tasks of provisioning, administering, and managing the physical computing resources have become increasingly complicated.
Examples of such large-scale systems include online merchants, internet service providers, online businesses such as photo processing services, corporate networks, cloud computing services, web-based hosting services, etc. These entities may maintain computing resources in the form of large numbers of computing devices (e.g., thousands of hosts) which are hosted in geographically separate locations and which are configured to process large quantities (e.g., millions) of transactions daily or even hourly. A conventional approach for harnessing these resources is the MapReduce model for distributed, parallel computing. In a MapReduce system, a large data set may be broken into smaller chunks, and the smaller chunks may be distributed to multiple nodes in a cluster. Each node in the cluster may implement the same algorithm for processing each respective chunk of the data set. In other words, a MapReduce system may represent a solution for performing homogeneous computations on heterogeneous input data.
While embodiments are described herein by way of example for several embodiments and illustrative drawings, those skilled in the art will recognize that embodiments are not limited to the embodiments or drawings described. It should be understood, that the drawings and detailed description thereto are not intended to limit embodiments to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope as defined by the appended claims. The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning “having the potential to”), rather than the mandatory sense (i.e., meaning “must”). Similarly, the words “include,” “including,” and “includes” mean “including, but not limited to.”